The present invention relates to the field of vascular catheters. More particularly, the present invention is related to a guide catheter which is adapted for insertion through a main artery into a branch artery ostium. Such catheters may be used to conduct a radio-opaque dye to the branch artery for diagnostic purposes, or for guiding a balloon catheter to a stenotic lesion in the branch artery for treatment purposes, such as in percutaneous transluminal coronary angioplasty.
In the case of the aorta, the coronary arteries which branch therefrom do so at angles approaching 90 degrees. The same can be said for the arteries of numerous other organs, such as renal and pulmonary arteries. A number of guide catheters having curved distal portions have been developed to facilitate engaging the ostia of such arteries. The Judkins, Amplatz, and Gamal guide catheters are examples of curves which are presently available.
In conventional coronary angioplasty procedure, a wire inserted into the guide catheter from the catheter's proximal end to its distal end straightens the curved portion of the catheter. The distal end of the catheter is then inserted into the patient's right femoral artery or, occasionally, the patient's right brachial artery, left brachial artery, or left femoral artery. The guide catheter and wire are then pushed up the artery and into the aorta until the distal end of the catheter is adjacent to the desired branch artery. The wire is withdrawn and the distal end of the catheter is maneuvered to engage the ostium of the branch artery.
After the guide catheter is positioned to engage the branch artery ostium, a balloon catheter is passed through the guide catheter and into the branch artery. The balloon portion of the balloon catheter is then maneuvered into position within the stenotic lesion and inflated to compact and split the material of the lesion, thereby increasing the diameter of the lumen through the lesion to facilitate the flow of blood through it. To enable the balloon catheter to be maneuvered into position, a guide wire may be attached to the distal end of the balloon catheter or passed through a lumen within the balloon catheter.
The guide catheter curves which are presently available have a tendency to engage the wall of the branch artery ostium and are easily dislodged from the ostium. FIGS. 1 and 2 show a catheter 1 having a Judkins left curve engaging the ostium 3 of the left main coronary artery 5. The Judkins curve extends from the point designated by reference number 7 to the tip 9 of the catheter 1.
As best seen in FIG. 2, the tip 9 of the catheter 1 engages an upper wall 11 of the artery 5 adjacent to the ostium 3. Engagement in this manner causes several problems. The tip 9 of the catheter 1 may cause trauma to the wall 11 of the artery 5 at the point of contact 13. In addition, the distal portion of the catheter 1 restricts the flow of blood from the aorta 15 into the artery 5, which may cause trauma to the portions of the heart supplied by the artery 5. Finally, when a balloon catheter 17 is passed through the catheter 1, the catheter 17 will contact the upper wall 11 of the artery 5, causing an area of friction 19. A force resulting from the area of friction 19, which the direction of is indicated by the arrow at reference number 21, tends to push the tip 9 out of the ostium 3 of the branch artery 5.
In many cases, the stenotic lesion (not shown) to be treated very nearly occludes the artery (not shown) in which it is located. Thus, the surgeon performing the angioplasty may meet with considerable resistance as he or she attempts to introduce the balloon catheter 17 into the lesion. A force resulting from overcoming that resistance also acts in the direction 21.
As best seen in FIG. 1 a force in direction 21, acting on the lever arm formed by the portion of the catheter 1 between an apex 23 and a lower bend 25, tends to bend the catheter 1 about the apex 23. As a result, the tip 9 of the catheter 1 is frequently disengaged from the ostium 3 of the artery 5. If this occurs before the balloon catheter 17 is properly positioned, the balloon catheter 17 and the catheter 1 may have to be withdrawn from the patient and the procedure begun again.
To avoid disengagement of the tip 9 of the catheter 1 from the ostium 3 of the artery 5, the catheter 1 may be maneuvered to extend further into the artery 5. While such extension decreases the tendency of the catheter 1 to disengage from the artery 5, it increases the possibility of causing trauma to the artery 9 and may cause the artery 9 to spasm.